angles {adehabitat} | R Documentation |
angles
computes the turning angles (in radians) between
consecutive moves from an object of class traj
. See examples
for a clearer definition.
angles(x, id = levels(x$id), burst = levels(x$burst), date = NULL, slsp = c("remove", "missing"))
x |
an object of class traj |
id |
a character vector giving the identity of the animals for which the angles are to be computed |
burst |
a character vector giving the identity of the circuits for which
the angles are to be computed (see traj ) |
date |
a vector of class POSIXct of length 2 (beginning, end)
delimiting the period of interest |
slsp |
a character string. If "remove" , successive
relocations located at the same place are replaced by a single
relocation, allowing the computation of the angles. If
"missing" , a missing value is returned for the angles when
successive relocations located at the same place. |
Returns a data frame with the following components:
id |
the identity of the animal |
x |
the x coordinate of the relocation at which the angle is computed |
y |
the y coordinate of the relocation at which the angle is computed |
date |
a vector of class POSIXct , giving the date at which
the relocation has been taken |
burst |
the id of the circuit (see help(traj) ) |
angles |
the turning angles between the successive moves. |
The function angles
is deprecated. The class ltraj
computes the turning angles automatically (see ltraj
).
Clement Calenge clement.calenge@oncfs.gouv.fr
Turchin, P. (1998) Quantitative analysis of movement. Measuring and modeling population redistribution in animals and plants. Sunderland, Massachusetts: Sinauer Associates.
speed
for computation of movement speeds,
traj
for additional information about objects of
class traj
## Not run: ## loads an object of class "traj" data(puechcirc) puechcir <- ltraj2traj(puechcirc) puechcir ## Gets a part of the trajectory of the wild boar named ## CH93 and draws it ## Also displays the turning angles toto <- puechcir[2:5,] plot(toto$x, toto$y, asp = 1, ylim = c(3158300, 3158550), pch = 16, main = "Turning angles between\nthree consecutive moves", xlab="X", ylab="Y") lines(toto$x, toto$y) lines(c(toto$x[2], 700217.6), c(toto$y[2], 3158310), lty=2) lines(c(toto$x[3],700289), c(toto$y[3],3158546), lty=2) ang1x <- c(700234.8, 700231.9, 700231, 700233.7, 700238.8, 700243.2) ang1y <- c(3158332, 3158336, 3158341, 3158347, 3158350, 3158350) ang2x <- c(700283.3, 700278.8, 700275.4, 700272.4, 700271.2, 700271.6, 700274.7) ang2y <- c(3158522, 3158522, 3158520, 3158517, 3158514, 3158508, 3158504) lines(ang1x, ang1y) lines(ang2x, ang2y) text(700216.1, 3158349, expression(theta[1]), cex=2) text(700247.7, 3158531, expression(theta[2]), cex=2) text(c(700301, 700231), c(3158399, 3158487), c("Beginning", "End"), pos=4) ## Computation of the turning angles with real data ## on wild boars plot(puechcir) ang <- angles(puechcir) ## The angles are in the column angles: ang[1:4,] ## End(Not run)